> On Wed, 19 Jul 2006 19:47:02 -0600, Virgil <virgil@comcast.net> wrote:> > >In article <tvbtb29qjsde0k18m272crf3092esavcsu@4ax.com>,> > Lester Zick <DontBother@nowhere.net> wrote:> >> >> On Wed, 19 Jul 2006 14:47:00 -0600, Virgil <virgil@comcast.net> wrote:> >> > >> > You have not read my reference to " logical tautologies" correctly.> >> >> >> >If, for example. "P and not P" would qualify as "false" does your > >> >gobledegook require its negation, "P or not P", to be true?> >> > >> "P and not P" is only universally false because it provides no> >> mechanical basis for alternatives since any "not (P and not P)"> >> converts into itself "not P and P". > >> >Not in any respectable logic it doesn't. According to de Morgan's laws,> >"not (P and not P)" is logically equivalent to "P or not P".> > It may be equivalent to lots of things. The issue is whether it> converts into itself mechanically.

According to de Morgan, and others, "not (P and not P)" and "P or not P" convert quite mechanically into each other but "not (P and not P)" and "not P and P" do not convert into each other in any way at all.